1. Field of the Invention
Embodiments of the present invention relate generally to semiconductor circuits containing fuse devices and, more specifically, to detection of a programming state of the fuse devices.
2. State of the Art
In integrated circuits it may be desirable to include a way to permanently store information about the integrated circuit. Fuses are often used to perform this function, wherein the fuse may be left unblown or the fuse may be blown. Some fuses may be blown with an electrical current while other fuses may be blown (or trimmed) with a laser. With this permanent information storage capability, semiconductor devices may be configured in different ways. For example, memories, such as Dynamic Random Access Memories, Static Random Access Memories, and Flash memories may have memory cells that are defective or do not meet performance standards. These defective memory cells may be bypassed and a substitution of spare memory cells may be made based on the programming of the fuse elements. Similarly, image sensors may include defective pixels, which may be compensated for based on the programming of the fuse elements.
Once the desired state of fuses on an integrated circuit is determined, the fuses may be programmed appropriately. It is useful to verify and sense the value of the programmed fuse both in operational modes and to verify that the fuse has been programmed successfully.
Many methods for sensing the programming state of fuse devices have been proposed. However, as semiconductor processing changes, these sensing methods have become more complex to implement. With the complexity, comes the requirement for increased die space for the sensing operation and, in many cases, increased power demand to perform the sensing operation.